The present invention relates to a ferrite chip bead array, and more particularly to a method for making a ferrite chip bead array having a structure capable of mounting on a surface of a circuit board.
Ferrite chip beads are well-known elements for removing undesirable electron waves by impedance based on the amount of the ferrite substrate- When current flows through the ferrite substrate, its frequency bank portion exhibiting a high reduced loss is absorbed in the ferrite substrate and discharged as a heat (according to the characteristic of ferrite substrate). Chip beads having such characteristics are embodied as elements mountable on a surface of a circuit board.
Referring to FIG. 3a, there is illustrated a conventional structure of chip beads. As shown in FIG. 3a, the chip bead has a double-layered sheet structure comprising a pair of ferrite sheets 1 constituting a ferrite substrate. Ferrite sheets 1 have facing inner surfaces printed with conductive paste (not shown). This sheet structure is cut to a desired size and then subjected to a baking. Thereafter, a plurality of outer electrodes 4' are attached to opposite side surfaces of the sheet structure to form the chip bead.
Unfortunately, such a chip bead structure requires a troublesome manufacturing processes because ferrite paste must be printed on each sheet. Moreover, inner conductors formed by printing conductive paste have a small area and a weak bonding force (due to structure). Moreover, there are problems with poor contact between inner conductors and outer electrodes and a tendency for outer electrodes to short-circuit from the ferrite substrate upon placement of the chip bead on a circuit board. Since inner conductors have a microstructure, they may be varied in electric characteristic, upon baking in the presence of a ferrite substrate.
These disadvantages prevent the above-mentioned chip bead structure from being used in electrical circuits requiring a high degree of reliability.